Subject:
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Re: Positioning
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Newsgroups:
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lugnet.robotics
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Date:
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Fri, 28 Jan 2000 01:39:04 GMT
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Viewed:
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1270 times
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Hi Pete,
I agree that the short sight is a problem. In my tests, I used wide strips.
Three times as wide as the RCX. And they were no more than a foot apart. So
missing them would have been difficult.
In real life, you could use similar tricks. For example, suppose you wanted
your robot to travel from the bedroom, into the living room, go over to the
corner and turn on the stereo. You could put a red rug in front of the stereo.
That's your landmark. People visiting you wouldn't think you're strange (like
they would if you layed colored strips of paper all over your house) and the
robot would have a (say) 1 foot by 3 foot target to hit.
You could also combine the mapping methods. Since the relationship of your
bedroom to your living room is unlikely to change, you could use a timing map
to navigate that. Then use a landmark map to zero in on the stereo. If your
girlfriend moves the stereo a few feet to make room for her plants, your robot
still finds the stereo.
And, of course, I'm hoping sonar will increase the range that landmarks can be
spotted. I'm not expecting it to be easy, and I don't even know what a
landmark would look like to sonar, but I'll find out more this summer.
And in talking about all this, it's starting to dawn on me that error handling
while traveling a map is relatively unexplored territory.
David Leeper (is still learning)
In lugnet.robotics, Pete Hardie <pete.hardie@dvsg.sciatl.com> writes:
> David Leeper wrote:
> >
> > Hi Pete,
> >
> > I was looking back over you post and realized I didn't answer a couple of • your
> > questions.
> >
> > > what are the steps leading up to "...when you get to the X..."?
> >
> > In the program I wrote there are only a few commands. Go forward. Turn left • at
> > landmark X. Turn right at landmark X.
> >
> > > And how does
> > > a bot determine that it has not found a landmark and needs to ask more
> > > directions.
> >
> > To be honest, I ignored the problem. Although I knew it could happen in
> > theory, in practice it never did, though I admit it was a limited set of
> > trials in a static environment. Offhand, I can think of a couple of possible
> > solutions. 1) Just stop moving after a given time limit or wheel rotation
> > count. 2) Have a set of landmarks that tell you when your lost, as in "If • you
> > see a McDonalds on your left, you've gone too far." Really, both answers are
> > the same. Have a mapping system to tell you when you're not correctly
> > following your mapping system.
> >
> > Again, I think the major flaw in all mapping systems that I've seen is
> > the "GO" command. Moving a robot is not acurate and the programmer has to • come
> > up with ways to deal with the inacuracy, whether its a timer system, a
> > rotation system, or landmark system.
>
> The main problem I'm seeing is that the legobot has very short sight, and so • it
> can
> only travel a certain distance before it is nearly sure to miss a landmark, • and
> then
> be lost.
>
> Also, in the Real World (tm), creatures with the limited senses of legobots • tend
> to
> use trail-following methods (ants and scent trails, etc) as the main path
> tracking,
> and perhaps landmarks to ID branching points. Creatures with long-range • senses
> use distance measures (bees and the honey-dance)
>
> --
> Pete Hardie | Goalie, DVSG Dart Team
> Scientific Atlanta |
> Digital Video Services Group |
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Message has 1 Reply:
 | | Re: Positioning
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| I have been watching this discussion with great interest. I was looking for a solution for this problem since I wanted to program a robot to find his way inside my apartment. The problem I found in the landmark system was that you don't have a (...) (25 years ago, 29-Jan-00, to lugnet.robotics)
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Message is in Reply To:
| | Re: Positioning
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| (...) The main problem I'm seeing is that the legobot has very short sight, and so it can only travel a certain distance before it is nearly sure to miss a landmark, and then be lost. Also, in the Real World (tm), creatures with the limited senses (...) (25 years ago, 27-Jan-00, to lugnet.robotics)
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